The present invention relates to a toner concentration detecting apparatus and a program storage medium for this apparatus, which is utilized for an image forming apparatus such as an electrophotographic printing apparatus used a liquid developing system.
Description of the Related Art
In a conventional image forming process using a developer that contains charged toner particles in a carrier liquid, the image quality is influenced by the concentration of toner particles and the electric charge of toner particles in the developer. Consequently, it is necessary that the concentration of toner particles in the developer is kept stable. Therefore, for example, Japanese Patent Application Laid-Open No. HEI 11-52737 discloses a technology that controls the toner concentration by detecting the electric conductivity of the developer, by using orthogonal electric fields. In another technology, a light transparency factor is used to control the toner concentration.
However, in the method detecting the light transparency factor, there are problems that dust on an optical window has to be cleaned and a method for a color image has to be established. And in the method detecting the electric conductivity, there exists the influence of ions (counter ions and excess ions) besides the toner particles. Therefore, there is a problem to be solved how to detect the electric conductivity by only the toner particles, by eliminating or decreasing the influence of the counter ions and excess ions.
Japanese Patent Application Laid-Open No. SHO 50-145146 discloses a toner concentration controlling method and an apparatus thereof, which disposes a pair of electrodes and applies an alternating pulse to the electrodes and detects a toner concentration by measuring the electric conductivity between the electrodes. However, in this method, the influence of ions contained in the developer is not considered, therefore there is a problem that the toner concentration can not be detected accurately.